Trying to estimate warning time in an actual mile or feet measurement is impossible since true warning time is influenced by many outside variables that have nothing to do with the radar detector itself. For example, the strength of the radar signal being transmitted, the direction the gun is pointed, the length of time it is transmitting, the positioning of the patrol car, and the influence of other objects around you may all affect how your radar detector receives a signal.

For these reasons, don’t expect your detector to achieve the same warning distance every time you encounter police radar. Just expect it to do what you bought it for: give you enough time to slow down and save yourself from receiving a speeding ticket.

Sensitivity refers to a radar detector’s ability to pick up police signals at the greatest distance. Selectivity refers to the detector’s ability to filter out signals that are not true police signals, yet operate on the same frequencies as police radar (i.e. security alarms, garage doors, automatic doors, etc.).

The filtration software built into K40 radar receivers features very unique microelectronic processors that minimize distractions that come from non-police radar transmitters. This helps give you the time you need to react to real potential threats, without the constant “falsing” that makes other detectors difficult to use in today’s challenging driving environments.

Radar detectors are essentially superheterodyne radio receivers. Like any radio, they’re passive devices that listen for microwave signals. The main difference is that they are specially-tuned to detect microwave frequencies transmitted by police radar and laser guns.

If a police car is not equipped with a radar or laser gun, a radar detector cannot possibly locate it. Also, if no signal is transmitted when you pass the police car, there won’t be any signals for your detector to receive.

Police may also use a sinister technique called “Instant-On” or “RF Hold.” During this type of encounter, an officer will wait until a targeted vehicle is within range to send a quick burst of radar to clock its speed. K40 radar detectors are sensitive enough to detect these brief, weak signals, but you have to pay attention and react quickly.

Speed signs – or speed reading boxes – are radar-based. Radar detectors are not radar jammers. Jamming radar is a federal offense and is prohibited by federal law nationwide. These informational-only speed readers, if working properly, should always detect and display your speed.

Speed signs – or speed reading boxes – are not used to issue traffic tickets or citations. As a result, these portable systems are not calibrated regularly and can “drift” away from the FCC-authorized frequencies. Because of this, when passing one of these signs that say Your Speed Is…,” you may or may not receive an alert. These devices are primarily placed in residential areas as a reminder to obey the speed limit.

POP Mode, when turned on, enables the detection of a special band of radar known as “POP.” This is a very short transmission signal that allows the user of a radar gun to capture a quick read of a vehicle’s speed prior to setting the gun to another band. K40 recommends that you keep the POP Radar Mode turned off for two reasons: 1) POP radar does not transmit long enough to gather information needed to issue a speeding ticket, and 2) keeping POP Mode “on” is known to cause far more false alerts than actual alerts.

No, we do not. The sale and use of radar jammers has been banned by the Federal Communications Commission (FCC) since 1997. The fines for each violation can reach up to $11,000.

Today, many high-end car manufacturers, such as Mercedes-Benz and BMW, are incorporating special tints into their windshields to protect the interior look and comfort of their cars. Unfortunately, this creates a very real problem for people who own portable radar detectors.

Putting tint of any kind on your windshield that contains metal film is essentially like putting a blanket over your radar detector. While radar microwave signals can still travel through fiberglass, plastic, and glass, they cannot penetrate metal. Some tints are worse than others, but if it contains metal of any kind, it will reduce the performance of any portable radar detector mounted inside the car.